Functional device and method of manufacturing the same

ABSTRACT

The invention provides a functional device having no cracks and capable of delivering good functional characteristics and a method of manufacturing the same. A functional layer ( 14 ) is formed by crystallizing an amorphous silicon layer as a precursor layer by laser beam irradiation. A laser beam irradiation conducts heat up to a substrate ( 11 ) to cause it to try to expand; a stress to be produced by the difference in thermal expansion coefficient between the substrate ( 11 ) and the functional layer ( 14 ) is shut off by an organic polymer layer ( 12 ) lower in thermal expansion coefficient than the substrate ( 11 ), thereby causing no cracks nor separations in the functional layer ( 14 ). The organic polymer layer ( 12 ) is preferably made of an acrylic resin, an epoxy resin, or a polymer material containing these that is deformed by an optical or thermal process to undergo a three-dimensional condensation polymerization, for higher compactness and hardness. Inserting a metal layer and an inorganic heat resistant layer between the substrate ( 11 ) and the functional layer ( 14 ) will permit a more powerful laser irradiation.

BACKGROUND OF THE INVENTION

The present invention relates to a functional device having a functionallayer, such as a thin film transistor, a dielectric capacitor, or asolar battery, and a method of manufacturing the same.

Since the pn junction of a hydrogenated amorphous silicon was developedin 1976, the hydrogenated amorphous silicon has been being activelystudied. The hydrogenated amorphous silicon has a structure in which adangling bond in a network made of silicon is terminated by hydrogen orfluorine, and its film can be formed at a low temperature equal to orlower than 300° C. Consequently, the film can be formed on a cheap glasssubstrate. A study is being made to apply the hydrogenated amorphoussilicon to a functional device such as a thin film transistor (TFT), asolar battery, or an optical sensor.

However, when the hydrogenated amorphous silicon is used as it is, inthe case of a TFT, only carrier mobility as low as about 0.1 to 0.5cm²/V·s can be obtained. In the case of a solar battery, there aredrawbacks such that doping efficiency is lower as compared with the caseof using polysilicon, and photoelectric conversion efficiencydeteriorates due to an increase in series resistance. In recent years, amethod of solving the problems by irradiating amorphous silicon formedon a glass substrate with an energy beam such as exicimer laser beam soas to be crystallized is being studied. Recently, crystallization of notonly semiconductors but also oxides performed by irradiation of anenergy beam is also being studied.

In the functional devices, a substrate for supporting a functional layermade of silicon, oxide, or the like is required to be light,shock-resistant, and flexible so as not to be broken when some stress isapplied. Conventionally, a silicon substrate, a glass substrate, or thelike is used. Recently, it is proposed to use a substrate made of anorganic material such as polyethylene terephthalate (PET) which islighter and more shock-resistant (refer to Japanese Unexamined PatentApplication Nos. 8-186267, 10-144930, and 10-144931).

An organic material substrate has, however, a thermal expansioncoefficient higher than that of a glass substrate or a siliconsubstrate. For example, as shown in FIG. 9, when a functional layer 103is crystallized by irradiating a laser beam LB as an energy beam,problems arises such that a substrate 101 expands by a heat transmittedvia an inorganic heat resistant layer 102 to the substrate 101, a verylarge stress instantaneously works on the functional layer 103, a crackoccurs and, in a worse case, peeling occurs. In this case, when theinorganic heat resistant layer 102 for suppressing thermal conductionfrom the functional layer 103 is formed with a thickness of 500 nm ormore, expansion of the substrate 101 is suppressed and peeling of thefunctional layer 103 can be suppressed to a certain extent. However,even small deformation of the substrate 101 causes a crack in theinorganic heat resistant layer 102 on the substrate 101, and peelingoccurs from the interface. In the case of manufacturing a functionaldevice by using the organic material substrate, therefore, sufficientcharacteristics and reliability cannot be obtained.

The invention has been achieved in consideration of the problems and itsobject is to provide a functional device having no crack and capable ofdelivering good functional characteristics and a method of manufacturingthe same.

SUMMARY OF THE INVENTION

A functional device of the invention has a functional layer provided onone of faces of a substrate and comprises: an inorganic heat resistantlayer which consists of one or a plurality of layers provided betweenthe substrate and the functional layer; and an organic polymer layerlower in thermal expansion coefficient than the substrate providedbetween the inorganic heat resistant layer and the substrate.

Another functional device according to the invention from which asubstrate is removed after the functional layer is provided on one offaces of the substrate, comprises: an organic polymer layer lower inthermal expansion coefficient than the substrate provided on one offaces of the functional layer; and an inorganic heat resistant layerwhich consists of one or a plurality of layers provided between theorganic polymer layer and the functional layer.

A method of manufacturing a functional device according to the inventionin which a functional layer is provided on a substrate, comprises: astep of forming an organic polymer layer having a thermal expansioncoefficient lower than that of the substrate on the substrate; a step offorming an inorganic heat resistant layer which consists of one or aplurality of layers on the organic polymer layer; and a step of formingthe functional layer on the inorganic heat resistant layer.

In the functional device according to the invention and the method ofmanufacturing the same, stress caused by the thermal expansion of thesubstrate can be shut off by the organic polymer layer which is providedbetween the substrate and the functional layer and having the thermalexpansion coefficient lower than that of the substrate, so thatoccurrence of cracks and peeling in the functional layer can beprevented.

In another functional device according to the invention, the organicpolymer layer having a thermal expansion coefficient lower than that ofthe substrate is provided. Thus, occurrence of a crack in the functionallayer due to the difference in the thermal expansion coefficient can beprevented.

Further, in the functional device according to the invention and themethod of manufacturing the same, it is preferable to provide the warpsuppression layer on the face of the substrate opposite to the face onwhich the functional layer is provided in order to suppress a warpcaused by thermal deformation of the substrate. The warp suppressionlayer may be a composite layer of a polymer layer made of an organicpolymer material and an inorganic heat resistant layer which consists ofone or two or more layers. Alternately, the warp suppression layer maybe constructed only by the polymer layer made of an organic polymermaterial.

Other and further objects, features and advantages of the invention willappear more fully from the following description.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross section showing the configuration of a thin filmtransistor according to a first embodiment of the invention.

FIGS. 2A, 2B, and 2C are cross sections each showing a manufacturingprocess of the thin film transistor shown in FIG. 1.

FIG. 3 is a cross section showing a modification of the thin filmtransistor illustrated in FIG. 1.

FIG. 4 is a cross section showing the configuration of a thin filmtransistor according to a second embodiment of the invention.

FIG. 5 is a cross section showing the configuration of a dielectriccapacitor according to a third embodiment of the invention.

FIG. 6 is a cross section showing the configuration of a thin filmtransistor according to a fourth embodiment of the invention.

FIG. 7 is a cross section showing the configuration of a solar batteryaccording to a fifth embodiment of the invention.

FIG. 8 is a cross section for explaining a manufacturing process of thesolar battery shown in FIG. 7.

FIG. 9 is a cross section for explaining conventional problems.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

Embodiments of the invention will be described in detail hereinbelowwith reference to the drawings.

First Embodiment

FIG. 1 shows a sectional configuration of a thin film transistor 10according to a first embodiment of the invention. The thin filmtransistor 10 has, for example, an organic polymer layer 12 and aninorganic heat resistant layer 13 which are stacked in this order on asubstrate 11. The thickness increases in accordance with the order ofthe inorganic heat resistant layer 13, the organic polymer layer 12, andthe substrate 11. On the inorganic heat resistant layer 13, a channelarea 14 a, a source area 14 b, and a drain area 14 c are formed as afunctional layer 14. The source area 14 b and the drain area 14 c areprovided so as to be isolated from each other and adjacent to thechannel area 14 a. A gate electrode 16 is formed on the channel area 14a via an insulating film 15. A source electrode 17 is electricallyconnected to the source area 14 b, and a drain electrode 18 iselectrically connected to the drain area 14 c.

The substrate 11 is made of, for example, an organic material.Preferable organic materials for forming the substrate 11 are polymermaterials such as polyesters e.g. PET (polyethylene terephthalate),polyethylene naphthalate, or polycarbonate, polyolefins such aspolypropylene, polyphenylene sulfides such as polyphenylene sulfide,polyamides, aromatic polyamides, polyether ketones, polyimides, acrylicresin, and PMMA (polymethyl methacrylate). Particularly, a generalplastic substrate made of polyethylene terephthalate, acetate,polyphenylene sulfide, polycarbonate, PES (polyether sulfone),polystyrene, nylon, polypropylene, polyvinyl chloride, acrylic resin,PMMA, or the like can be suitably used.

The substrate 11 is preferably thin and has a thickness of, for example,about 200 μm to give the device flexibility and to reduce the size ofthe device.

The organic polymer layer 12 has a thickness of, for example, about 10μm and is made of an organic material having a thermal expansioncoefficient higher than that of the substrate 11. For example, when aplastic board is used as the substrate 11, it is preferable to use aso-called hard coating material for the plastic board, which maintainssome hardening up to 200° C. of relatively high temperature and hasdenseness and hardness. Examples of such a coating material are anacrylic resin, an epoxy resin, and polymer materials containing any ofthe resins thereof, each of which is bonded by three-dimensionalcondensation polymerization that occurs when the material is deformed byan optical or thermal process.

Examples of the coating material containing an acrylic resin are apolymer material containing an acrylic resin and a composite polymerplastic material containing an acrylic resin and another resin. Examplesof such a coating material which is preferably used are variouspolyfunctional acrylate compounds such as ethylene glycoldi(meth)acrylate, neopentyl glycol di(meth)acrylate, bisphenol-Adi(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritoltri(meth)acylate, and dipentaerythritol, bifunctional acrylate compoundsprepared by causing a reaction between 2,2-bis(4′-hydroxyphenyl)hexafluoro propane or alkylene glycol ether and isocyanate alkyl(meth)acrylate, and the like. The kind of a comonomer to be subjected tocopolymerization varies according to the application field, and anycopolymerizable monomer can be used.

Each of the coating materials is usually made of a monomer having amolecular weight of about 100 to 1000 and having a single unsaturatedsite or two, three, or a number of unsaturated sites. With respect tothe composition of the coating material, preferably, 99 to 100 percentby weight is reactive components and a solid material. More preferably,99.9 to 100 percent by weight is reactive components and a solidmaterial. Most preferably, 100 percent by weight is reactive componentsand a solid material. Solid materials include a polymer material and anonvolatile solid material such as colloidal silica. One of properpolymer materials is cellulose acetate butyrate. A coating materialwhich can be converted to a solid matter by 100% when exposed toultraviolet rays is preferable. In each of the materials, aphotopolymerization initiator of an amount necessary to enable thecoating material to be hardened by light irradiation is contained. Eachof the materials may contain a predetermined amount of latentultraviolet ray shielding material such as resorcinol monobenzoate.

Examples of the coating material containing an epoxy resin are anorganic silicon compound, and a substance generically called an epoxysilane as the hydrolysate of the organic silicon compound. Examples ofthe coating material are γ-glycidoxypropyl trimethoxysilane,γ-glycidoxypropyl trietoxysilane, γ-glycidoxypropyl trimethoxy ethoxysilane, γ-glycidoxypropyl triacetoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxy silane, β-(3,4-epoxycyclohexyl)ethyl triethoxy silane,β-(3,4-epoxycyclohexyl)ethyl trimethoxy ethoxy silane,β-(3,4-epoxycyclohexyl)ethyl triacetoxy silane, γ-glycidoxypropyldimethoxy methyl silane, γ-glycidoxypropyl diethoxy methyl silane,γ-glycidoxypropyl dimethoxy ethoxy methyl silane, γ-glycidoxypropyldiacetoxy methyl silane, β-(3,4-epoxycyclohexyl)ethyl dimethoxy methylsilane, β-(3,4-epoxycyclohexyl)ethyl diethoxy methyl silane,β-(3,4-epoxycyclohexyl)ethyl dimethoxy ethoxy methyl silane,β-(3,4-epoxycyclohexyl)ethyl diacetoxy methyl silane, γ-glycidoxypropyldimethoxy ethyl silane, γ-glycidoxypropyl diethoxy ethyl silane,γ-glycidoxypropyl dimethoxy ethoxy ethyl silane, γ-glycidoxypropyldiacetoxy ethyl silane, γ-(3,4-epoxycyclohexyl)ethyl dimethoxy ethylsilane, β-(3,4-epoxycyclohexyl)ethyl diethoxy ethyl silane,β-(3,4-epoxycyclohexyl)ethyl dimethoxy ethoxy ethyl silane,β-(3,4-epoxycyclohexyl)ethyl diacetoxy ethyl silane, γ-glycidoxypropyldimethoxy isopropyl silane, γ-glycidoxypropyl diethoxy isopropyl silane,γ-glycidoxypropyl dimethoxy ethoxy isopropyl silane, γ-glycidoxypropyldiacetoxy isopropyl silane, β-(3,4-epoxycyclohexyl)ethyl diethoxyisopropyl silane, β-(3,4-epoxycyclohexyl)ethyl diethoxy isopropylsilane, β-(3,4-epoxycyclohexyl)ethyl dimethoxy ethoxy isopropyl silane,β-(3,4-epoxycyclohexyl)ethyl diacetoxy isopropyl silane,γ-glycidoxypropyl methoxy dimethyl silane, γ-glycidoxypropyl ethoxydimethyl silane, γ-glycidoxypropyl methoxy ethoxy dimethyl silane,γ-glycidoxypropyl acetoxy dimethyl silane, β-(3,4-epoxycyclohexyl)ethylmethoxy dimethyl silane, β-(3,4-epoxycyclohexyl)ethyl ethoxy dimethylsilane, β-(3,4-epoxycyclohexyl)ethyl methoxy ethoxy dimethyl silane,β-(3,4-epoxycyclohexyl)ethyl acetoxy dimethyl silane, γ-glycidoxypropylmethoxy diethyl silane, γ-glycidoxypropyl ethoxy diethyl silane,γ-glycidoxypropyl methoxy ethoxy diethyl silane, γ-glycidoxypropylacetoxy diethyl silane, β-(3,4-epoxycyclohexyl)ethyl methoxy diethylsilane, β-(3,4-epoxycyclohexyl)ethyl ethoxy diethyl silane,β-(3,4-epoxycyclohexyl)ethyl methoxy ethoxy diethyl silane,β-(3,4-epoxycyclohexyl)ethyl acetoxy diethyl silane, γ-glycidoxypropylmethoxy di-isopropyl silane, γ-glycidoxypropyl ethoxy di-isopropylsilane, γ-glycidoxypropyl, methoxy ethoxy di-isopropyl silane,γ-glycidoxypropyl acetoxy di-isopropyl silane,β-(3,4-epoxycyclohexyl)ethyl methoxy di-isopropyl silane,β-(3,4-epoxycyclohexyl)ethyl ethoxy di-isopropyl silane,β-(3,4-epoxycyclohexyl)ethyl methoxy ethoxy di-isopropyl silane,β-(3,4-epoxycyclohexyl)ethyl acetoxy di-isopropyl silane,γ-glycidoxypropyl methoxy ethoxy methyl silane, γ-glycidoxypropylacetoxy methoxy methyl silane, γ-glycidoxypropyl acetoxy ethoxy methylsilane, β-(3,4-epoxycyclohexyl)ethyl methoxy ethoxy methyl silane,β-(3,4-epoxycyclohexyl)ethyl methoxy acetoxy methyl silane,β-(3,4-epoxycyclohexyl)ethyl ethoxy acetoxy methyl silane,γ-glycidoxypropyl methoxy ethoxy ethyl silane, γ-glycidoxypropyl acetoxymethoxy ethyl silane, γ-glycidoxypropyl acetoxy ethoxy ethyl silane,β-(3,4-epoxycyclohexyl)ethyl methoxy ethoxy ethyl silane,β-(3,4-epoxycyclohexyl)ethyl methoxy acetoxy ethyl silane,β-(3,4-epoxycyclohexyl)ethyl ethoxy acetoxy ethyl silane,γ-glycidoxypropyl methoxy ethoxy isopropyl silane, γ-glycidoxypropylacetoxy methoxy isopropyl silane, γ-glycidoxypropyl acetoxy ethoxyisopropyl silane, β-(3,4-epoxycyclohexyl)ethyl methoxy ethoxy isopropylsilane, β-(3,4-epoxycyclohexyl)ethyl methoxy acetoxy isopropyl silane,β-(3,4-epoxycyclohexyl)ethyl ethoxy acetoxy isopropyl silane, glycidoxymethyl trimethoxysilane, glycidoxy methyl triethoxysilane, α-glycidoxyethyl trimethoxysilane, α-glycidoxy methyl trimethoxysilane, β-glycidoxyethyl trimethoxysilane, β-glycidoxy methyl trimethoxysilane,α-glycidoxypropyl trimethoxysilane, α-glycidoxypropyl triethoxysilane,β-glycidoxypropyl trimethoxysilane, β-glycidoxypropyl triethoxysilane,γ-glycidoxypropyl tripropoxysilane, γ-glycidoxypropyl tributoxy silane,γ-glycidoxypropyl triphenoxysilane, α-glycidoxy butyl trimethoxysilane,α-glycidoxy butyl triethoxysilane, β-glycidoxy butyl trimethoxysilane,β-glycidoxy butyl triethoxysilane, γ-glycidoxy butyl trimethoxysilane,γ-glycidoxy butyl triethoxysilane, (3,4-epoxycyclohexyl)methyltrimethoxysilane, (3,4-epoxycyclohexyl)methyl triethoxysilane,β-(3,4-epoxycyclohexyl)ethyl tripropoxysilane,β-(3,4-epoxycyclohexyl)ethyl triptoxysilane,β-(3,4-epoxycyclohexyl)ethyl triphenoxysilane,γ-(3,4-epoxycyclohexyl)propyl trimethoxysilane,γ-(3,4-epoxycyclohexyl)propyl triethoxysilane,δ-(3,4-epoxycyclohexyl)butyl trimethoxysilane,δ-(3,4-epoxycyclohexyl)butyl triethoxysilane, glycidoxy methyl methyldimethoxysilane, glycidoxy methyl methyl diethoxysilane, α-glycidoxyethyl methyl dimethoxysilane, α-glycidoxy ethyl methyl diethoxysilane,β-glycidoxy ethyl methyl dimethoxysilane, β-glycidoxy ethyl methyldiethoxysilane, α-glycidoxypropyl methyl dimethoxysilane,α-glycidoxypropyl methyl diethoxysilane, β-glycidoxypropyl methyldimethoxysilane, β-glycidoxypropyl methyl diethoxysilane,γ-glycidoxypropyl methyl dimethoxysilane, γ-glycidoxypropyl methyldiethoxysilane, γ-glycidoxypropyl methyl dipropoxysilane,γ-glycidoxypropyl methyl dibutoxysilane, γ-glycidoxypropyl methyldimethoxy ethoxysilane, γ-glycidoxypropyl methyl diphenoxysilane,γ-glycidoxypropyl ethyl dimethoxysilane, γ-glycidoxypropyl ethyldiethoxysilane, γ-glycidoxypropyl ethyl dipropoxysilane,γ-glycidoxypropyl vinyl dimethoxysilane, and γ-glycidoxypropyl vinyldiethoxysilane.

One of the coating materials may be used or, according to a purpose, amixture of two or more kinds of the coating materials may be used. Anyof the coating materials may be mixed with another silane compound.Examples of silane compounds are various trialkoxysilane,triacyloxysilane, or trialkoxy alkoxysilane compounds such asmethyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane,vinyltriethoxysilane, vinyltriacetoxysilane,vinyltrimethoxyethoxysilane, γ-methacryloxypropyl trimethoxy silane,aminomethyl trimethoxysilane, 3-aminopropyl trimethoxysilane,3-aminopropyl triethoxy silane, phenyl trimethoxy silane, phenyltriethoxy silane, γ-chloropropyl trimethoxy silane, γ-mercapto propyltriethoxy silane, and 3,3,3-trifluoro propyl trimethoxy silane,dialkoxysilane compounds such as dimethyl dimethoxysilane, diphenyldimethoxysilane, methyl phenyl dimethoxysilane, methyl vinyldimethoxysilane, and dimethyl diethoxysilane, and tetrafunctional silanecompounds such as methyl silicate, ethyl silicate, isopropyl silicate,n-propyl silicate, n-butyl silicate, t-butyl silicate, and sec-butylsilicate.

A number of so-called hard coating materials exist such as a polymermaterial of an acrylic resin which is highly dense and very hardachieved by bonding by three-dimensional condensation polymerization, aplastic material of a composite polymer containing an acrylic resin andanother resin, and a hard coating material made of an organic silicideand an epoxy resin of the hydrolyte of the organic silicide. Obviously,the above-described group of materials are just examples.

In a method of forming the organic polymer layer 12, as necessary,fillers and water or organic solvent are mixed with the acrylic resin,epoxy resin, or a polymer material containing any of the resins, anddispersed by a paint shaker, a sand mill, a pearl mill, a ball mill, anattriter, a rolling mill, a high-speed impeller disperser, a jet mill, ahigh-speed impact mill, an ultrasonic disperser, or the like, therebyobtaining a coating material.

The coating material is applied so as to form a single layer or multiplelayers on one of the faces or both faces of the substrate 11 by using acoating method such as air doctor coating, blade coating, knife coating,reverse coating, transfer roll coating, gravure roll coating, kiss-rollcoating, cast coating, spray coating, slot orifice coating, calendercoating, electrodeposition coating, dip coating, or die coating, or aprinting method of, for example, letterpress printing such asflexographic printing, intaglio printing such as direct gravure printingor offset gravure printing, plate printing such as offset printing, orstencil printing such as screen printing. In the case where the coatingmaterial contains a solvent, after application, the coating material isthermally dried. Subsequently, the coating material applied on thesubstrate is heated or irradiated with an energy beam, for example,ultraviolet rays from an ultraviolet lamp so as to be set. In the caseof using ultraviolet rays as the energy beam, a photopolymerizationinitiator is necessary.

The inorganic heat resistant layer 13 has a thickness of, for example,about 300 nm and is made of a material having thermal conductivity lowerthan that of the functional layer 14 and having a thermal expansioncoefficient lower than that of the organic polymer layer 12. In thiscase, the inorganic heat resistant layer 13 is made of an oxide such assilicon oxide (SiO_(x)), a nitride such as silicon nitride (SiN_(x)), anoxynitride such as silicon oxynitride (SiO_(x)N_(y)), or the like or mayhave a multilayer structure of those materials. An inorganic carbidesuch as silicon carbon (SiC), a carbon material such as DLC (DiamondLike Carbon), or the like may be also used.

As described above, the thermal coefficients of expansion are, from thelowest to the highest, the inorganic heat resistant layer 13, organicpolymer layer 12, and substrate 11.

Each of the channel area 14 a, source area 14 b, drain area 14 c is madeof, for example, polycrystalline silicon (polysilicon), so that highcarrier mobility can be obtained. The polycrystal includes so-calledquasi-single crystal described in the specification of Japanese PatentApplication No. 9-30552. The quasi-single crystal is constructed by aplurality of crystal grains each of which is almost a single crystal.The crystal grains are priority-oriented in a direction of one plane andneighboring crystal grains are lattice-aligned at least in a part of thegrain boundary.

In each of the source area 14 b and the drain area 14 c, for example, ann-type impurity such as phosphorus (P) is doped. Each of the channelarea 14 a, source area 14 b, and drain area 14 c has a thickness of, forexample, about 30 nm. The insulating film 15 is made of, for example,silicon oxide. Each of the gate electrode 16, source electrode 17, anddrain electrode 18 is made of, for example, aluminum (Al).

Referring to FIGS. 2A, 2B, and 2C, a method of manufacturing the thinfilm transistor 10 will now be described.

First, as shown in FIG. 2A, on the substrate 11, a polymer materialcontaining an acrylic resin, for example, dipentaerithritol is dispersedby a paint shaker, thereby obtaining a coating material. The coatingmaterial is coated by air doctor coating. After that, the coatingmaterial coated on the substrate is set by being heated or irradiatedwith an energy beam, for example, ultraviolet rays from an ultravioletlamp by using a photopolymerization initiator, thereby forming theorganic polymer layer 12. Subsequently, for example, the substrate 11 onwhich the organic polymer layer 12 is formed is stamped into apredetermined shape, washed, and dried. Then, the inorganic heatresistant layer 13 is formed on the organic polymer layer 12 by, forexample, reactive sputtering. After that, an amorphous silicon layer 21is formed as a precursor layer of the functional layer 14 on theinorganic heat resistant layer 13 by, for example, sputtering.

After forming the amorphous silicon layer 21, for example, as shown inFIG. 2B, a photoresist film 22 having openings corresponding to areaswhich become the source area 14 b and the drain area 14 c is formed onthe amorphous silicon layer 21. For example, by using the photoresistfilm 22 as a mask, the amorphous silicon layer 21 is exposed to anatmosphere containing an ionized gas of phosphine (PH₃) to dopephosphorus to the areas which become the source area 14 b and the drainarea 14 c. After doping phosphorus, the photoresist film 22 is removed.

After removing the photoresist film 22, for example, as shown in FIG.2C, the amorphous silicon layer 21 is irradiated with a laser beam LB soas to be heated in a nitrogen gas (N₂) atmosphere. By the operation, theamorphous silicon layer 21 is crystallized, and the functional layer 14,that is, the channel area 14 a, source area 14 b, and drain area 14 care formed. In this case, as the laser beam LB, it is preferable to usean excimer laser beam. The wavelength may be any of 350 nm of XeF, 308nm of XeCl, 248 nm of KrF, 193 nm of ArF, and the like. In the case ofusing a laser beam of a short wavelength such as an excimer laser beam,the energy density is preferably 80 mJ/cm² or higher for the reason thatthe amorphous silicon layer 21 can be sufficiently heated, and thefunctional layer 14 having excellent crystallizability can be obtained.

Heat generated in the amorphous silicon layer 21, that is, thefunctional layer 14 by the irradiation of the laser beam LB dissipatestoward the substrate 11. However, since the inorganic heat resistantlayer 13 having low thermal conductivity is provided between thefunctional layer 14 and the substrate 11, the heat transmission towardthe substrate 11 is suppressed by the inorganic heat resistant layer 13.

By the heat transmitted via the inorganic heat resistant layer 13, thesubstrate is thermal expanded, and a stress occurs. However, since theorganic polymer layer 12 having a thermal expansion coefficient lowerthan that of the substrate 11 is provided between the inorganic heatresistant layer 13 and the substrate 11, the stress is further shut off.It prevents occurrence of a crack in the functional layer 14 and peelingof the functional layer 14.

After forming the functional layer 14, as shown in FIG. 1, theinsulating film 15 is formed on the functional layer 14 by, for example,reactive sputtering. Contact holes corresponding to the source and drainare formed in the insulating film 15 and then the gate electrode 16,source electrode 17, and drain electrode 18 are formed by, for example,vapor deposition.

In the embodiment as described above, the organic polymer layer 12 isformed between the substrate 11 and the functional layer 14.Consequently, even when the laser beam LB is emitted at the time offorming the functional layer 14, the stress which occurs due to thethermal expansion of the substrate 11 is shielded by the organic polymerlayer 12, so that occurrence of a crack and peeling in the functionallayer 14 can be prevented. Thus, the excellent functional layer 14 madeof polysilicon can be formed on the substrate 11 made of an organicmaterial at high yield.

Further, in the embodiment, the thickness increases in accordance withthe order of the inorganic heat resistant layer 13, the organic polymerlayer 12, and substrate 11. Particularly, the structure is employed inwhich the inorganic heat resistant layer 13 is formed as thin aspossible and the organic polymer layer 12 is formed thicker than theinorganic heat resistant layer 13 and is formed thinner than thesubstrate 11 in order to be crashworthy without losing flexibility.Thus, the light, shock-resistant thin film transistor 10 havingexcellent characteristics can be obtained.

Although the thin film transistor 10 in which the channel area 14 a,insulating film 15, and gate electrode 16 are provided in this order onthe substrate 11 has been described in the foregoing embodiment, asshown in the thin film transistor 10A in FIG. 3, the gate electrode 16,insulating film 15, and channel area 14 a may be provided in this orderon the substrate 11. In this case as well, effects similar to those ofthe foregoing embodiment can be obtained.

Second Embodiment

FIG. 4 shows a sectional configuration of a thin film transistor 10Baccording to a second embodiment of the invention. In the thin filmtransistor 10B, for example, between a substrate 61 and a functionallayer 66, an inorganic heat resistant layer 64, an organic polymer layer62, a metal layer 65, and an inorganic heat resistant layer 63 arestacked in order. The inorganic heat resistant layer 63 is provided onthe top face of the organic polymer layer 62 in a manner similar to thefirst embodiment, and the inorganic heat resistant layer 64 is providedon the under face of the organic polymer layer 62. The inorganic heatresistant layers 63 and 64 are made of, for example, similar materials.The functional layer 66 has a channel area 66 a, a source area 66 b, anda drain area 66 c. A gate electrode 68 is formed on the channel area 66a via an insulating film 67, a source electrode 69 is electricallyconnected to the source area 66 b, and a drain electrode 70 iselectrically connected to the drain area 66 c. The functional layers 66and the electrodes 68 to 70, and the neighboring functional layer 66 areelectrically insulated from each other via an insulating interlayer 71.

Since the substrate 61, organic polymer layer 62, and inorganic heatresistant layers 63 and 64 correspond to the substrate 11, organicpolymer layer 12, and inorganic heat resistant layer 13, respectively,in the first embodiment, their detailed description will not berepeated.

The metal layer 65 is made of, for example, a metal having excellentheat conductivity. As a metal material of the metal layer 65, forexample, Al is suitably used. Other than Al, Au, Ag, Cu, Pt, Ta, Cr, Mo,W, or the like can be used. The metal layer 65 may have a multilayerstructure of two or more layers as the above-described inorganic heatresistant layers 63 and 64. The plurality of metal layers 65 may beproperly inserted between the plurality of inorganic heat resistantlayers 63 provided on the organic polymer layer 62.

It is also possible to provide one of the inorganic heat resistant layer64 and metal layer 65.

The functional layer 66, channel area 66 a, source area 66 b, and drainarea 66 c correspond to the functional layer 14, channel area 14 a,source area 14 b, and drain area 14 c in the first embodiment,respectively. The insulating film 67, gate electrode 68, sourceelectrode 69, and drain electrode 70 also correspond to the insulatingfilm 15, gate electrode 16, source electrode 17, and drain electrode 18in the first embodiment, respectively. In addition, in the secondembodiment, in order to maintain electrical insulation among theneighboring electrodes 68 to 70 and among the neighboring layersfunctioning as the functional layer 66, as shown in FIG. 4, theinsulating interlayer 71 is provided. The insulating interlayer 71 ismade of, for example, a resin material such as silicon oxide orpolyimide.

The thin film transistor 10B having such a configuration can bemanufactured by a method according to the first embodiment as follows.

First, in a manner similar to the inorganic heat resistant layer 13, theinorganic heat insulating layer 64 is formed on the substrate 61. In amanner similar to the organic polymer layer 12, the organic polymerlayer 62 is formed. Subsequently, the metal layer 65 is formed on theorganic polymer layer 62 by, for example, DC sputtering. Further, theinorganic heat resistant layer 63 and the functional layer 66 are formedin a manner similar to the inorganic heat resistant layer 13 and thefunctional layer 14, respectively.

Heat generated in the functional layer 66 by the irradiation of thelaser beam LB dissipates toward the substrate 61. However, since theinorganic heat resistant layers 63 and 64 having low heat conductivityare provided between the functional layer 66 and the substrate 61, theheat transmission to the substrate 61 is doubly suppressed by theinorganic heat resistant layers 63 and 64. Further, in the embodiment,since the metal layer 65 having high heat conductivity is providedbetween the organic polymer layer 62 and the inorganic heat resistantlayer 63, heat stored in the inorganic heat resistant layers 63 and 64dissipates from the metal layer 65.

After forming the functional layer 66, by a known method, the insulatingfilm 67 and the gate electrode 68 are formed on the channel area 66 a.After that, for example, the insulating interlayer 71 is formed on theentire face, and contact holes are formed in the insulating interlayer71. Finally, the source electrode 69 and the drain electrode 70 areformed. In such a manner, the thin film transistor 10A shown in FIG. 4is obtained.

As described above, according to the embodiment, the inorganic heatresistant layers 63 and 64 having low heat conductivity are providedbetween the functional layer 66 and the substrate 61, so that the heattransmission to the substrate 61 is doubly suppressed and heat expansionof the substrate 61 can be prevented with reliability. Further, sincethe metal layer 65 having high heat conductivity is provided between theorganic polymer layer 62 and the inorganic heat resistant layer 63, heataccumulated in the heat resistant layers 63 and 64 is dissipated fromthe metal layer 65, so that heat transmission to the substrate 61 can beprevented. By suppressing the thermal expansion of the substrate 61 morestrongly as described above, an effect similar to that of the firstembodiment can be enhanced. In other words, heating with an energy beamhaving higher energy density can be realized.

Third Embodiment

FIG. 5 shows a sectional configuration of a dielectric capacitor 30according to the second embodiment of the invention. The dielectriccapacitor 30 has, in a manner similar to the thin film transistor 10 ofthe first embodiment, the substrate 11, organic polymer layer 12, andinorganic heat resistant layer 13. The same components are designated bythe same reference numerals as those of the first embodiment and theirdetailed description will not be repeated.

On the inorganic heat resistant layer 13, for example, a lower electrode31 made of indium tin oxide (ITO), a dielectric layer 32 as a functionallayer, and an upper electrode 33 made of ITO are stacked in this orderfrom a side close to the inorganic heat resistant layer 13. Thedielectric layer 32 is, for example, polycrystalline and contains aferroelectric material such as solid solution (PZT) of lead titanate(PbTiO₃) and lead zirconate (PbZrO₃), barium titanate (BaTiO₃), or alayer structure oxide containing bismuth (Bi). Those ferroelectricmaterials do not have to have stoichiometric composition.

Referring now to FIG. 5, a method of manufacturing the dielectriccapacitor 30 having such a configuration will be described.

First, in a manner similar to the first embodiment, the organic polymerlayer 12 and the inorganic heat resistant layer 13 are sequentiallyformed on the substrate 11. Subsequently, on the inorganic heatresistant layer 13, the lower electrode 31 is formed by, for example,sputtering. On the lower electrode 31, an oxide layer mainly in anamorphous state that is not illustrated is formed as a precursor layerof the dielectric layer 32 by, for example, sputtering. On thenot-illustrated oxide layer, the upper electrode 33 is formed by, forexample, sputtering.

After that, for example, the not-illustrated oxide layer is heated witha laser beam emitted from a side close to the upper electrode 33 in anitrogen gas atmosphere so as to be crystallized, thereby forming thedielectric layer 32. The parameters of the laser beam are similar tothose in the first embodiment. In the third embodiment as well, asdescribed in the first embodiment, heat transmission to the substrate 11is suppressed by the inorganic heat resistant layer 13, a stressgenerated by the thermal expansion of the substrate 11 is shut off bythe organic polymer layer 12, and occurrence of a crack and peeling inthe dielectric layer 32 is prevented.

As described above, in the embodiment as well, the organic polymer layer12 is formed between the substrate 11 and the dielectric layer 32.Consequently, in a manner similar to the first embodiment, theoccurrence of a crack and peeling in the dielectric layer 32 can beprevented, and the excellent dielectric film 32 can be formed on thesubstrate 11 made of the organic material at high yield. Thus, the lightand shock-resistant dielectric capacitor 30 having excellentcharacteristics can be obtained.

Fourth Embodiment

FIG. 6 shows a sectional configuration of a thin film transistor 10Caccording to a fourth embodiment of the invention. According to thefourth embodiment, on the back side of the substrate 11 of the thin filmtransistor 10 in the first embodiment, a warp suppression layer 81 forsuppressing a warp in the substrate 11 which occurs in association withthe thermal expansion is provided. The same components as those in thefirst embodiment are designated by the same reference numerals and theirdescription will not be repeated. Only different points will bedescribed.

In the fourth embodiment, the warp suppression layer 81 takes the formof a composite layer of a polymer layer 81A made of an organic polymermaterial and an inorganic heat resistant layer 81B comprised of one orplural layers.

Preferably, the polymer layer 81A is made of the same polymer materialas that of the organic polymer layer 12 and is formed with the samethickness as that of the organic polymer layer 12. Preferably, in amanner similar to the inorganic heat resistant layer 13, the inorganicheat resistant layer 81B is also made of a material containing at leastone material selected from a group consisting of oxide, nitride, andoxynitride and formed with the same thickness as that of the inorganicheat resistant layer 13. Obviously, the polymer layer 81A and theinorganic heat resistant layer 81B may be made of materials differentfrom those of the organic polymer layer 12 and the inorganic heatresistant layer 13, respectively, as long as any of the above materialsis used.

In a following functional layer fabricating process, the followingconditions have to be satisfied since it is important to suppressoccurrence of a warp in the substrate 11 by a thermal stress by the warpsuppression layer 81. Specifically, a thermal displacement ratio in arange from a room temperature to 150° C. is set to 5% or lower at thetime point when the warp suppression layer 81 is formed on the back sideof the substrate 11 and the organic polymer layer 12 and the inorganicheat resistant layer 13 are formed on the surface of the substrate 11. Athermal displacement ratio in a range from a room temperature to 150° C.is set similarly to 5% or lower at the time point when the functionallayer 14 is formed on the surface of the substrate 11. When each of thethermal displacement ratios is 5% or lower, the object can be achievedwithout a problem in each of the subsequent processes.

The thermal displacement ratio is defined in the specification as “avalue calculated by (a/b)×100 where “a” denotes the maximum warp at eachof temperatures when one end of the substrate is fixed to a referenceface and “b” denotes the maximum length of the substrate”. Thetemperature of 150° C. is set since the temperature is the upper limitfrom the process point of view when the substrate 11 is made of aplastic material.

In the thin film transistor 10C of the embodiment, in the process (referto FIG. 2A) of forming the organic polymer layer 12 and the inorganicheat resistant layer 13 on the substrate 11 described in the firstembodiment, when the same layers are simultaneously formed on the backside of the substrate 11, the warp suppression layer 81 can be formed.The following processes of forming the amorphous silicon layer 21 andthe functional layer 14, emitting the laser beam LB, and the like aresimilar to those of the first embodiment.

In the fourth embodiment, with the above configuration, in addition tothe effect of the first embodiment, an effect such that the warp(curvature) of the substrate 11 caused by a difference in thermalcoefficients of expansion between layers such as the substrate 11 andthe functional layer 14 can be suppressed is obtained. In the fourthembodiment, the warp suppression layer 81 is constructed by the polymerlayer 81A and the heat resistant layer 81B. It is also possible to omitthe inorganic heat resistant layer 81B and construct the warpsuppression layer 81 only by the polymer layer 81A.

Fifth Embodiment

FIG. 7 shows a sectional configuration of a solar battery 40 accordingto a fifth embodiment of the invention. The solar battery 40 has, in amanner similar to the thin film transistor 10 of the first embodiment,the substrate 11, organic polymer layer 12, and inorganic heat resistantlayer 13. The same components as those in the first embodiment aredesignated by the same reference numerals and their detailed descriptionwill not be repeated.

On the inorganic heat resistant layer 13, for example, a functionallayer 41 made of polysilicon is formed. The functional layer 41 has, forexample, a p-type area 41 a, an n⁺ type area 41 b provided on the p-typearea 41 a, and a p⁺ type area 41 c provided on the p-type area 41 a andisolated from the n⁺ type area 41 b. The p-type area 41 a has athickness of, for example, about 1 μm to 49 μm and contains 1×10¹⁵ to1×10¹⁸ atoms/cm³ of a p-type impurity such as boron (B). The n⁺ typearea 41 b has a thickness of, for example, about 0.05 μm to 1 μm andcontains an n-type impurity such as phosphorus at a density as high asabout 1×10¹⁹ atoms/cm³. The p⁺ type area 41 c has a thickness of, forexample, about 0.05 μm to 1 μm and contains a p-type impurity such asboron at a density as high as about 1×10¹⁹ atoms/cm³.

The functional layer 41 has, for example, under the p-type area 41 a, ap⁺ type area 41 d having a thickness of about 1 μm and containing ap-type impurity such as boron at a density as high as about 1×10¹⁹atoms/cm³. The p⁺ type area 41 d is used to increase the photoelectricconversion efficiency by reflecting electrons generated in the p-typearea 41 a. By making the functional layer 41 of polysilicon, high dopingefficiency is obtained, series resistance can be reduced, andphotoelectric conversion efficiency can be increased.

On the functional layer 41, for example, an antireflection film 42 madeof titanium oxide (TiO₂) is formed. An opening is formed in theantireflection film 42 in correspondence with the n⁺ type area 41 b, anda cathode 43 made of, for example, aluminum is electrically connected tothe n⁺ type area 41 b via the opening. An opening corresponding to thep⁺ type area 41 c is also formed in the antireflection film 42, and ananode 44 made of, for example, aluminum is electrically connected to thep⁺ type area 41 c via the opening. On the antireflection film 42,cathode 43, and anode 44, for example, a protective substrate 46 made ofpolyethylene terephthalate is disposed via an adhesion layer 45 made ofethylene-vinylacetate.

Referring now to FIGS. 7 and 8, a method of manufacturing the solarbattery 40 will be described.

First, as shown in FIG. 8, in a manner similar to the first embodiment,the organic polymer layer 12 and the inorganic heat resistant layer 13are sequentially formed on the substrate 11. On the inorganic heatresistant layer 13, an amorphous silicon layer 51 is formed as aprecursor layer of the functional layer 41 by, for example, sputtering.The amorphous silicon layer 51 is exposed, for example, in an atmospherecontaining an ionized gas of diborane (B₂H₆), and boron (B) is doped.

On the amorphous silicon layer 51, for example, by sputtering, anamorphous silicon layer 52 is further formed as a precursor layer of thefunctional layer 41. After that, for example, a side close to theamorphous silicon layer 52 is irradiated with the laser beam LB in thenitrogen gas atmosphere to thereby heat the amorphous silicon layers 51and 52. By the operation, the amorphous silicon layers 51 and 52 arecrystallized and become the functional layer 41. In this case, a portioncorresponding to the amorphous silicon layer 51 becomes the p⁺ type area41 d. The parameters of the laser beam are similar to those in the firstembodiment. In the fifth embodiment as well, as described in the firstembodiment, heat transmission to the substrate 11 is suppressed by theinorganic heat resistant layer 13, the stress generated by thermalexpansion of the substrate 11 is shut off by the organic polymer layer12, and occurrence of a crack and peeling is prevented.

As shown in FIG. 7, a part corresponding to the amorphous silicon layer52 in the functional layer 41 is exposed to, for example, an atmosphereof an ionized gas of diborane, thereby forming the p-type area 41 a.After that, for example, by using the lithography technique, a part ofthe p-type area 41 a is exposed to the atmosphere containing the ionizedgas of diborane to form the p⁺ type area 41 c. Further, for example, byusing the lithography technique, a part of the p-type area 41 a isexposed to an atmosphere containing an ionized gas of phosphine, therebyforming the n⁺ type area 41 b.

After forming the functional layer 41 as described above, on thefunctional layer 41, the antireflection film 42 is formed by, forexample, sputtering, and openings are formed in correspondence with then⁺ type area 41 b and the p⁺ type area 41 c. After that, for example, bysputtering, the cathode 43 and the anode 44 are formed in correspondencewith the n⁺ type area 41 b and the p⁺ type area 41 c, respectively.Finally, on the antireflection film 42, the protective substrate 46 isadhered via the adhesive layer 45.

In the embodiment as well, the organic polymer layer 12 is formedbetween the substrate 11 and the functional layer 41. In a mannersimilar to the first embodiment, the occurrence of a crack and peelingin the functional layer 41 can be prevented, so that the excellentfunctional layer 41 made of polysilicon can be formed on the substrate11 made of an organic material at high yield. Therefore, the light,shock-resistant solar battery 40 having excellent characteristics can beeasily obtained.

Further, concrete examples of the invention will be described in detail.

EXAMPLE 1

In Example 1, first, a substrate having a thickness of 200 μm made ofpolyethylene terephthalate was prepared. On the substrate, an organicpolymer layer was formed by applying dipentaerithritol to a thickness ofabout 6 μm and irradiating the material with ultraviolet rays to carryout condensation polymerization into a three-dimensional structure.After that, the substrate on which the organic polymer layer is formedwas stamped in a disk shape having a diameter of about 10 cm, washed,and dried.

Subsequently, the substrate was disposed in a vacuum chamber, and thepressure in the chamber was set to about 1.3×10⁻⁵ Pa by using a vacuumpump. After that, oxygen gas (O₂) and argon gas (Ar) were charged intothe chamber, and an inorganic heat resistant layer made of silicon oxidewas formed on the organic polymer layer to a thickness of about 300 nmby reactive sputtering. After forming the inorganic heat resistantlayer, argon gas was passed into the chamber and an amorphous siliconlayer as a precursor layer was formed on the inorganic heat resistantlayer to a thickness of about 30 nm by sputtering. To form the inorganicheat resistant layer and the amorphous silicon layer, a facing targetsystem for applying a voltage between targets disposed on one side ofthe substrate was used.

After forming the amorphous silicon layer, the substrate was taken outfrom the vacuum chamber, the amorphous silicon layer was irradiated witha line beam of an XeCl excimer laser with an energy density of 280mJ/cm² at the maximum in the nitrogen gas atmosphere and crystallized,thereby forming a polysilicon layer as the functional layer. After that,the polysilicon layer was observed at a magnification of 90 times by anoptical microscope. No crack and peeling was seen in the polysiliconlayer, and an excellent crystal layer was formed.

As a comparative example of Example 1, except that the organic polymerlayer is not formed, the polysilicon layer was formed in a mannersimilar to Example 1. The polysilicon layer was also observed in amanner similar to Example 1. A number of cracks were seen in thepolysilicon layer and a part was completely peeled off.

It was understood that, by forming the organic polymer layer between thesubstrate and the amorphous silicon layer, even if the amorphous siliconlayer is irradiated with a laser beam, an excellent polysilicon layercan be formed on the substrate made of an organic material withoutcausing a crack and peeling.

EXAMPLE 2

In this example, a polysilicon layer was formed in a manner similar toExample 1 except that an electrode made of ITO was formed between theinorganic heat resistant layer and the amorphous silicon layer. Thepolysilicon layer was also observed in a manner similar to Example 1. Nocrack and peeling was seen in the polysilicon layer and an excellentcrystal layer was formed.

EXAMPLE 3

In this example, a polysilicon layer was formed in a manner similar toExample 1 except that after forming the amorphous silicon layer, priorto irradiation of a laser beam, phosphorus was doped at a high densityinto the amorphous silicon layer. After carrying the substrate into aPECVD (Plasma Enhanced Chemical Vapor Deposition) chamber by using aload lock, the phosphorus was doped by exposing the amorphous siliconlayer to a plasma while passing a mixture gas of phosphine gas andhydrogen gas (Hs) containing 1% by volume of phosphine gas. Thepolysilicon layer was also observed in a manner similar to Example 1 andno cracks and peeling were found. It was understood that the excellentn⁺ type polysilicon layer can be formed on the substrate made of anorganic material.

EXAMPLE 4

In this example, a polysilicon layer was formed in a manner similar toExample 1 except that, after forming the amorphous silicon layer, boronwas doped at high density into the amorphous silicon layer prior toirradiation of a laser beam. Boron was doped in a manner similar toExample 3 except that a diborane gas was used in place of a phosphinegas. The polysilicon layer was also observed in a manner similar toExample 1 and no cracks and peeling were seen. That is, it wasunderstood that the excellent p⁺ type polysilicon layer can be formed onthe substrate made of an organic material.

EXAMPLE 5

In this example, first, in a manner similar to Example 1, the organicpolymer layer and the inorganic heat resistant layer were sequentiallyformed on the substrate. Subsequently, in an argon gas atmosphere, alower electrode made of ITO was formed on the inorganic heat resistantlayer by sputtering. On the lower electrode, a mainly amorphous-stateoxide layer containing lead (Pb), titanium (Ti), and zirconium (Zr) wasformed as a precursor layer by sputtering in the argon gas atmosphere ata room temperature. After that, in the argon gas atmosphere, an upperelectrode made of ITO was formed on the oxide layer by sputtering. Forformation of the lower electrode, oxide layer, and upper electrode, thefacing target system was used.

After forming the upper electrode, a side close to the upper electrodewas irradiated with a line beam of an XeCl excimer laser at an energydensity of 280 mJ/cm² at the maximum in a nitrogen gas atmosphere, theoxide layer was crystallized, and a dielectric layer was formed as afunctional layer containing a polycrystal PZT. The dielectric layer wasobserved in a manner similar to Example 1 and no cracks and peeling wereseen. That is, it was understood that the excellent dielectric layer canbe formed on the substrate made of an organic material.

EXAMPLE 6

In this example, a p⁺ type polysilicon layer was formed in a mannersimilar to Example 4 except that dipentaerythritol (warp suppressionlayer) was applied to 6 μm on the back face of a substrate made of PET(polyethylene terephthalate), having a thickness of 200 μm, and having alength of 10 cm. When the polysilicon layer was observed in a mannersimilar to Example 1, no cracks and peeling were seen. That is, it couldbe confirmed that an effect similar to that of Example 4 can be obtainedalso in the case where the warp suppression layer is formed on the backof the substrate.

EXAMPLE 7

In this example, a polysilicon layer was formed in a manner similar toExample 1 except that a composite polymer material of polyacrylic esterand phenoxy resin was applied to a thickness of about 8 μm. Thepolysilicon layer was observed in a manner similar to Example 1, and nocracks and peeling were seen. That is, it could be confirmed that aneffect similar to that of Example 1 can be obtained also in the casewhere the organic polymer layer is made of the other material.

EXAMPLE 8

A polysilicon layer was formed in a manner similar to Example 2 exceptthat a composite polymer material of polyacrylic ester and phenoxy resinwas applied to a thickness of about 8 μm. The polysilicon layer wasobserved in a manner similar to Example 1, and no cracks and peelingwere seen. That is, it could be confirmed that an effect similar to thatof Example 2 can be obtained also in the case where the organic polymerlayer is made of the other material.

EXAMPLE 9

A n⁺ type polysilicon layer was formed in a manner similar to Example 3except that a composite polymer material of polyacrylic ester andphenoxy resin was applied to a thickness of about 8 μm. The polysiliconlayer was observed in a manner similar to Example 1, and no cracks andpeeling were seen. That is, it could be confirmed that an effect similarto that of Example 3 can be obtained also in the case where the organicpolymer layer is made of the other material.

EXAMPLE 10

A p⁺ type polysilicon layer was formed in a manner similar to Example 4except that a composite polymer material of polyacrylic ester andphenoxy resin was applied to a thickness of about 8 μm. The polysiliconlayer was observed in a manner similar to Example 1, and no cracks andpeeling were seen. That is, it could be confirmed that an effect similarto that of Example 4 can be obtained also in the case where the organicpolymer layer is made of the other material.

EXAMPLE 11

A p⁺ type polysilicon layer was formed in a manner similar to Example 10except that a composite polymer material of polyacrylic ester andphenoxy resin was applied to a thickness of 8 μm on the back face of asubstrate made of PET (polyethylene terephthalate), having a thicknessof 200 μm, and a length of 10 cm. The polysilicon layer was observed ina manner similar to Example 1, and no cracks and peeling were seen. Thatis, it could be confirmed that an effect similar to that of Example 10can be obtained also in the case where the warp suppression layer isformed on the back of the substrate.

Although the present invention has been described above by theembodiments and examples, the invention is not limited to the foregoingembodiments and examples but can be variously modified. For example, thecase where the functional layers 14 and 41 are made of silicon has beendescribed in the first and third embodiments. The functional layers 14and 41 may be made of another semiconductor containing silicon such assilicon germanium. The invention can be also applied to a case where thefunctional layer is made of other semiconductor such as III-V compoundsemiconductor.

Further, in the second embodiment, the example where the dielectriclayer 32 is made of a ferroelectric material has been described.Alternately, the dielectric layer 32 may be made of a high dielectricmaterial.

Further, in the foregoing embodiments and examples, the functional layeris made of polycrystal. However, the invention can be widely appliedalso to the case where the functional layer is in a crystalline state ofsingle crystal, crystallite, or the like. That is, the invention can bewidely applied to the case where the functional layer has crystallinity.The functional layer may be crystalline in at least a part like acomposite body of polycrystal and amorphous substance.

In addition, the foregoing embodiments and examples have been describedwith respect to the case where the inorganic heat resistant layer ismade of silicon oxide, silicon nitride, or silicon oxynitride. Insteadof the materials or together with the materials, at least one of oxide,nitride, or oxynitride of, for example, aluminum, zirconium, or the likemay be contained.

Further, in the foregoing embodiments and examples, the precursor layeris irradiated with a laser beam. Alternately, other energy beams such aselectron beam may be used.

Moreover, although the functional device has been concretely describedas an example in the foregoing embodiments, the invention can be widelyapplied to a functional device with the other configuration as long asthe functional device has an inorganic heat resistant layer between asubstrate and a functional layer and has an organic polymer layerbetween the inorganic heat resistant layer and the substrate. Forexample, the invention can be also applied to memories such as FeRAM(Ferroelectric Random Access Memories) and functional devices other thana dielectric capacitor having a functional layer containing an oxide.

Further, although the embodiments have been described with respect tothe functional device having the substrate 11, the substrate 11 may beremoved after fabricating the functional device. The invention can beapplied also to a functional device which does not have the substrate11.

As described above, in the functional device or the method ofmanufacturing the functional device according to the invention, theorganic polymer layer having a thermal expansion coefficient lower thanthat of the substrate is provided between the functional layer and thesubstrate. Consequently, for example, even when an energy beam isemitted to form the functional layer, the stress generated by thethermal expansion of the substrate can be shut off by the organicpolymer layer, so that occurrence of cracks and peeling in thefunctional layer can be prevented. Thus, effects are produced such thatthe light, shock-resistant functional device having excellentcharacteristics and capable of using the substrate made of, for example,an organic material can be obtained.

Further, in the invention, by providing the warp suppression layer onthe face of the substrate opposite to the face on which the functionallayer is provided, a warp caused by thermal deformation of the substratecan be effectively suppressed.

In the functional device according to another aspect of the invention,since the organic polymer layer is provided on one of the faces of thefunctional layer, even when the energy beam is irradiated to form thefunctional layer, the stress generated by the thermal expansion can beshut off by the organic polymer layer, so that the occurrence of cracksand peeling in the functional layer can be prevented. Therefore, thesubstrate made of an organic material having a high thermal expansioncoefficient can be used at the time of manufacture.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

1. A functional device in which a functional layer is provided on one offaces of a substrate, comprising: an inorganic heat resistant layerwhich consists of one or a plurality of inorganic compound layersprovided between the substrate and the functional layer; and an organicpolymer layer lower in thermal expansion coefficient than the substrateprovided between the inorganic heat resistant layer and the substrate.2. A functional device according to claim 1, wherein the thickness ofeach layers increases in accordance with order of the inorganic heatresistant layer, the organic polymer layer, and the substrate.
 3. Afunctional device according to claim 1, further comprising anotherinorganic heat resistant layer which is different from the inorganicheat resistant layer and consists of one or a plurality of inorganicheat resistant layers provided between the substrate and the organicpolymer layer.
 4. A functional device according to claim 3, wherein eachof the inorganic heat resistant layer and the another inorganic heatresistant layer has thermal conductivity lower than that of thefunctional layer.
 5. A functional device according to claim 3, whereineach of the inorganic heat resistant layer and the another inorganicheat resistant layer has thermal expansion coefficient lower than thatof the organic polymer layer.
 6. A functional device according to claim3, wherein each of the inorganic heat resistant layer and the anotherinorganic heat resistant layer includes at least one kind of materialselected from the group of an oxide, a nitride, and an oxynitride.
 7. Afunctional device according to claim 3, wherein each of the inorganicheat resistant layer and the another inorganic heat resistant layer ismade of an inorganic carbide or a carbon material.
 8. A functionaldevice according to claim 1, further comprising a metal layer whichconsists of one or a plurality of layers provided between the organicpolymer layer and the inorganic heat resistant layer.
 9. A functionaldevice according to claim 1, wherein the organic polymer layer is madeof an acrylic resin, an epoxy resin, or a polymer material containingthe acrylic resin or the epoxy resin.
 10. A functional device accordingto claim 1, wherein the functional layer has crystallinity.
 11. Afunctional device according to claim 1, wherein the functional layercontains a semiconductor or an oxide.
 12. A functional device accordingto claim 1, wherein the functional layer contains silicon.
 13. Afunctional device according to claim 1, further comprising an electrodefor the functional layer, provided between the functional layer and theinorganic heat resistant layer.
 14. A functional device from which asubstrate is removed after a functional layer is provided on one offaces of the substrate, comprising: an organic polymer layer lower inthermal expansion coefficient than the substrate provided on one offaces of the functional layer; and an inorganic heat resistant layerwhich consists of one or a plurality of layers provided between theorganic polymer layer and the functional layer.
 15. A functional deviceaccording to claim 14, further comprising another inorganic heatresistant layer which is different from the inorganic heat resistantlayer and which consists of one or a plurality of layers providedbetween the substrate and the organic polymer layer.
 16. A functionaldevice according to claim 14, further comprising a metal layer whichconsists of one or a plurality of layers provided between the organicpolymer layer and the inorganic heat resistant layer.
 17. A method ofmanufacturing a functional device in which a functional layer isprovided on a substrate, comprising: a step of forming an organicpolymer layer having a thermal expansion coefficient lower than that ofthe substrate on the substrate; a step of forming an inorganic heatresistant layer which consists of one or a plurality of layers on theorganic polymer layer; and a step of forming the functional layer on theinorganic heat resistant layer.
 18. A method of manufacturing afunctional device according to claim 17, further comprising a step offorming another heat resistant layer on the substrate, which isdifferent from the heat resistant layer and consists of one or aplurality of layers before the organic polymer layer is formed.
 19. Amethod of manufacturing a functional device according to claim 17,further comprising a step of forming a metal layer which consists of oneor a plurality of layers on the organic polymer layer before the heatresistant layer is formed.
 20. A method of manufacturing a functionaldevice according to claim 17, wherein the step of forming the organicpolymer layer includes: a step of forming a precursor of the organicpolymer layer; and a step of forming an organic polymer layer byirradiating the precursor with an energy beam to make condensationpolymerization occur in the organic polymer layer.
 21. A method ofmanufacturing a functional device according to claim 20, wherein theenergy beam is emitted from an ultraviolet lamp including a wavelengthof an ultraviolet region.
 22. A method of manufacturing a functionaldevice according to claim 17, wherein the step of forming the functionallayer includes: a step of forming a precursor of the functional layer;and a step of forming the functional layer by irradiating the precursorwith an energy beam.
 23. A method of manufacturing a functional deviceaccording to claim 22, wherein the precursor is crystallized byirradiating an energy beam.
 24. A method of manufacturing a functionaldevice according to claim 22, wherein a laser beam is used as the energybeam.
 25. A method of manufacturing a functional device according toclaim 24, wherein a laser beam of a short wavelength having an energydensity of 80 mJ/cm² or higher is applied as the laser beam.
 26. Afunctional device in which a functional layer is provided on one offaces of a substrate, comprising: an inorganic heat resistant layerwhich consists of one or a plurality of layers provided between thesubstrate and the functional layer; an organic polymer layer lower inthermal expansion coefficient than the substrate provided between theinorganic heat resistant layer and the substrate; and a warp suppressionlayer for suppressing a warp of the substrate provided on a face facingthe face on which the functional layer is provided.
 27. A functionaldevice according to claim 26, wherein the warp suppression layer is madeof an organic polymer material.
 28. A functional device according toclaim 26, wherein the warp suppression layer is a composite layercomprised of a polymer layer made of an organic polymer material and aninorganic heat resistant layer which consists of one or two or morelayers.
 29. A functional device according to claim 27 or 28, wherein theorganic polymer material is an acrylic resin, an epoxy resin or amaterial containing the acrylic resin or the epoxy resin.
 30. Afunctional device according to claim 28, wherein the inorganic heatresistant layer contains at least one kind of material selected from agroup of an oxide, a nitride, and an oxynitride.
 31. A functional deviceaccording to claim 28, wherein each of the inorganic heat resistantlayer is made of an inorganic carbide or a carbon material.
 32. A methodof manufacturing a functional device in which a functional layer isprovided on a substrate, comprising: a step of forming a warp suppresslayer for suppressing a warp in the substrate on the back side of thesubstrate; a step of forming an organic polymer layer having a thermalexpansion coefficient lower than that of the substrate on the surface ofthe substrate; a step of forming an inorganic heat resistant layer whichconsists of one or a plurality of layers on the organic polymer layer;and a step of forming the functional layer on the inorganic heatresistant layer.
 33. A method of manufacturing a functional deviceaccording to claim 32, wherein a thermal displacement ratio in a rangefrom a room temperature to 150° C. is set to 5% or lower at the timepoint when the warp suppression layer is formed on the back side of thesubstrate and the organic polymer layer and the inorganic resistantlayer are formed on the surface of the substrate.
 34. A method ofmanufacturing a functional device according to claim 32, wherein athermal displacement ratio in a range from a room temperature to 150° C.is set to 5% or lower at the time point when the warp suppression layeris formed on the back side of the substrate, and the organic polymerlayer, the inorganic heat resistant layer, and the functional layer areformed on the surface of the substrate.
 35. A method of manufacturing afunctional device according to claim 32, further comprising a step offorming a metal layer which consists of one or a plurality of layers onthe organic polymer layer before the inorganic heat resistant layer isformed.
 36. A method of manufacturing a functional device according toclaim 32, wherein the step of forming the organic polymer layerincludes: a step of forming a precursor of the organic polymer layer;and a step of forming the organic polymer layer by irradiating theprecursor with an energy beam to make condensation polymerization occurin the organic polymer.
 37. A method of manufacturing a functionaldevice according to claim 36, wherein the energy beam is emitted from anultraviolet lamp including a wavelength of an ultraviolet region.
 38. Amethod of manufacturing a functional device according to claim 32,wherein the step of forming the functional layer includes: a step offorming a precursor layer of the functional layer on the inorganic heatresistant layer; and a step of forming the functional layer byirradiating the precursor layer with an energy beam.
 39. A method ofmanufacturing a functional device according to claim 38, wherein theprecursor layer is crystallized by irradiating an energy beam.
 40. Amethod of manufacturing a functional device according to claim 39,wherein a laser beam is used as the energy beam.
 41. A method ofmanufacturing a functional device according to claim 40, wherein a laserbeam of a short wavelength having an energy density of 80 mJ/cm² orhigher is applied as the laser beam.
 42. A method of manufacturing afunctional device according to claim 32, further comprising a step offorming an electrode for the functional layer between the inorganic heatresistant layer and the functional layer.